Technical Field
This disclosure relates to a sheet feeding device that feeds a sheet such as a paper, and an image forming apparatus including the sheet feeding device. The image forming apparatus corresponds to, for example, a copier, printer, facsimile machine, and a multi-functional apparatus including at least two functions of the copier, printer, and facsimile machine.
Related Art
Various image forming apparatuses such as copiers, printers, and printing machines include a sheet feeding device that feeds sheets such as papers. Such a sheet feeding device is known to employ an air adsorption method using an air blowing device. For example, by performing the air adsorption method in the above-described sheet feeding device, air is blown from the air blowing device toward an uppermost sheet of a sheet bundle loaded on a sheet loading portion (such as a bottom plate). The uppermost sheet blown by the air blowing device is lifted and attracted to an air drawing device. While the uppermost sheet is being attracted by the air drawing device, a sheet transfer belt conveys the uppermost sheet in a sheet conveying direction.
To be specific, a known sheet feeding device includes a sheet loading portion (a bottom plate), a reference face (a downstream side end), an air blowing device, an air drawing device, a sheet transfer belt (a sheet attraction belt), and so forth.
Among sheets of the sheet bundle loaded on the sheet loading portion, the uppermost sheet is lifted over the sheet bundle and is adsorbed by the air drawing device while the air blowing device is blowing air to an end of the uppermost sheet. By so doing, the uppermost sheet is attracted to the sheet transfer belt. As the sheet transfer belt rotates, the uppermost sheet attracted to the sheet transfer belt is conveyed in the sheet conveying direction.
Another known sheet feeding device includes a shutter to open and close an opening formed in the reference face (the downstream side end) in order to lift the sheet stably by the air blowing device even when the number of sheets loaded on the sheet loading portion (the bottom plate) becomes smaller. To be more specific, the shutter opens the opening formed in the reference face (the downstream side end) as the number of sheets loaded on the sheet loading portion decreases.